OBJECTIVE: Comparative study of survival of gastrointestinal cancer patients in Israel, as a function of ethnic background, and immune response. Israel has well-defined ethnic populations differing genetically (HLA) as well as in cultural habits (diet, family size, use of health services). Marked differences in the incidence of GI cancer have been recorded between these populations, i.e., the incidence among East European Jews being much higher than that among Afro-Asian Jews. There is also a suggested difference in the fatality rate among these populations. In the proposed study approximately 200 new GI cancer patients will be studied prospectively in the course of 4 years. Their survival according to their ethnic background will be determined and correlated with immune status during the course of the disease. The following immune parameters will be determined sequentially: a) General immune response - humoral response (serum Ig, antibodies to Fc and Fab) and cellular immune response (lymphoid populations, skin delayed hypersensitivity and mitogen response). b) Tumor immunity - 1) Sensitization to tumor cells and/or antigens. 2) Analysis of lymphoreticular cell infiltration around tumor and cellular response to autologous tumor tissues. In the analysis of the data, age, sex, stage and type of tumor will all be taken into consideration.